1. Field of the Invention
The invention relates to a seatbelt control device and, more particularly, to a seatbelt control device that controls a force limiter mechanism that restricts the load applied to an occupant by the tension of a seatbelt to or below a certain amount at the time of an emergency.
2. Description of the Related Art
A seatbelt retractor device provided in a vehicle restrains an occupant's body from moving forward relative to the vehicle at the time of a sharp deceleration state of the vehicle, as a spool for winding up and letting out the seatbelt is locked by a lock mechanism.
Besides, a seatbelt retractor device equipped with a pretensioner mechanism that forcibly winds the seatbelt has already been proposed. There also has been proposed a seatbelt retractor device equipped with a force limiter mechanism that lessens the restraining force by utilizing the twist of a torsion bar, or the like, when an occupant's body that moves forward by an inertia force pulls the seatbelt by an excessively large force (when an excessively large force is applied to an occupant's body via the seatbelt).
Besides, as for the force limiter mechanism, a selectable force limiter mechanism in which the load corresponding to the restraining force can be selected is provided in some seatbelt retractor devices.
For example, a technology described in Japanese Patent Application Publication-No. 2007-84042 (JP-A-2007-84042) lessens the restraining force by utilizing the magnitude of the force that twists the torsion bar. Then, there is proposed a technology of a force limiter mechanism in which the magnitude of load at which the lessening of the restraining force is started can be selected between a predetermined high load and a predetermined low load by utilizing a micro gas generator (MGG). In this force limiter mechanism, the load at which the lessening of the restraining force is started is set at the high load in the initial state of setting, and then if the body size of an occupant is small, the technology switches it to the low load.
However, in the case of a construction in which a degree of a collision is determined, and in which if it is determined that the collision is a gentle collision, a gas generator is activated to switch the set load value, it sometimes happens that the switching of the load at which to start the lessening of the restraining force is delayed if the determination regarding the degree of collision is delayed.